But, even if they do all of those things, can they hold on to their new No. 1 ranking all the way through to January 8th?

No.

Here are a few reasons why:

Voters Are Fickle

Listen: Last week, the voters thought Alabama was not quite as good as USC. Then No. 2 Alabama stomped No.8 Michigan 41-14, while No. 1 USC only stomped unranked Hawaii 49-10. The voters have now decided that Alabama is much better than USC. Some of this certainty comes from the fact that the voters in the poll do not want to be wrong about Michigan.

But what if Michigan isn't very good? What if Big Blue loses, say, three of its next six (Air Force, UMass, No. 24 Notre Dame, Purdue, Illinois and No. 13 Michigan State) and drops out of the polls? What if Alabama struggles with Arkansas while USC crushes Stanford? What if an insulted LSU squad goes on a rampage while the complacent Tide go on cruise control? It's a long season, and voters overreact. Will the voters support Alabama over every other school for the next four months? Possible, but unlikely.

Opposition

The SEC is the toughest conference in college football. The Tide have eight conference games remaining, including those against No. 3 LSU and No. 10 Arkansas. They not only have to win all of these—which will be difficult enough—but they have to do so convincingly enough to keep the voters in the polls happy. That's doable. It's just not easy. Which is to say that it is possible, but unlikely.

Early Peak?

In NFL circles, it is a well-accepted truism that the best team in September and October is not likely to be the best team in January and February. (Ask Aaron Rodgers and Eli Manning.) It's not just about momentum. It's about other teams gunning for you, and having time to figure you out. Alabama must be the best team in college football in order to repeat as BCS Champions. They must be better by an even wider margin to do so as an undefeated team—which is probably what it will take to hold that ranking all the way to January 8. Again: Possible, but unlikely.

The Breaks of the Game

This is football. Above all else, you have to avoid injury. If you want to go undefeated, you have to avoid even the two-weeks-off kind of injuries. That's not about skill. That's about luck. Can the Tide be that lucky? Again: It is possible, but unlikely.

So there you have four different things that each have to go right for the Crimson Tide to hold the No. 1 ranking all the way through to January 8th. Can all four work out, all the time, in the same season?